Fluid pressure controlled signal switch



,1953 w. P. BILLINGS- 2,648,733

FLUID PRESSURE CONTROLLED SIGNAL SWITCH Filed Dec. 5 1 951 William R Billings INVENTOR.

Patented Aug. 11, 1953 UNITED STATES PATENT OFFICE FLUID PRESSURE CONTROLLED SIGNAL SWITCH 4 Claims.

This invention relates to certain new and useful improvements in a fluid pressure responsive switch such as is used to operate electric warning signals and which, while it is usable in many difierent ways, is primarily adapted for use on motor vehicles where, for example, it performs as a stop light switch on the one hand and as an oil pressure indicating switch on the other hand.

More specifically, the invention coinprehends the adoption and use of a switch which is of simplified construction and is such that it provides a highly practical and durable device which is economical, can be brought into use without disturbing or altering the presently used wiring systems and in which manufacturers, mechanics and users will flnd their respective needs fully met and efiectually available.

In carrying out the principles of the invention, one objective is to dispense with the currently used rubber and equivalent seals by substituting therefor a practical and reliable pressure type seal, the construction of the latter being such that it shall not be appreciably affected by either high or lower pressures or by temperatures varying from hot to cold.

Another object of the invention is to provide a signal switch which is characterized by a casing, circuit make and break means for off and on operation housed in casing, and fluid pressure responsive means carried by said casing and operatively cooperating with said circuit make and break means, said pressure responsive means when operated by fluid under pressure being self-sealing, whereby to prevent any fluid from by-passing said latter means and getting into said casing.

A further object of the invention has to do with pressure responsive means which is incorporated in and forms an integral part or the casing at one end of the casing and is made up essentially of a cylinder and a plunger which is reciprocable in the cylinder, said cylinder having an abutment and said plunger having a shoulder which matches and conformingly and tightly engages the abutment, the abutment serving as a stop for the plunger and also as a seat for the shoulder, whereby to perfect the fluid pressure actuated seal and providing a construction susceptible of properly coping with both low and extremely high pressures without imposing any additional strain, wear or tear on the parts of the over-all switch.

A still further object of the invention has to do with a plunger which is provided with an endless groove, there being a packing ring fitted in said groove, the ring coacting in wiping contact with the wall of the cylinder and serving in and of itself to keep fluid out of the switch chamber, thereby providing a low pressure seal at this point and functioning to keep the plunger properly lubricated even when the switch has not been in use for some time, say several months or more.

Then, too, it is a further object of the invention, in one of its forms, to provide a heavyduty self-polishing needle coacting with spring cliptype contact fingers which in action render the coacting contacts substantially self-cleaning, whereby to avoid sticking.

Furthermore, it is an object of the invention to employ a switch mechanism casingv whose exterior surfaces are fiat-faced whereby to provide a desired tool gripping surface to accommodate a wrench used in attaching and detaching the casing.

The obvious and most important object of the over-all switch construction is in reference to the effective fluid tight seal which is obtainable due to the special coaction of the plunger and cylinder structural characteristics, whereby to minimize the possibility of fluid getting into the chamber which houses the fixed and movable contacts and spring means associable therewith.

Other objects, features and advantages will become more readily apparent from the following description and the accompanying sheet of illustrative drawings.

In the accompanying sheet of drawings wherein like numerals are employed to designate like parts throughout the views:

Figure 1 is a view primarily in elevation, but partly in section, showing a hydraulic brake master-cylinder and showing more importantly, the improved fluid pressure responsive switch for controlling a signal, for example a stop light signal.

Figure 2 is an enlarged central longitudinal sectional view, with portions appearing in elevation, revealing the complete switch construction with the switch open.

Figure 3 is a cross section on the line t-fi of Figure 2, looking in the direction of the arrows;

Figure 4 is an exaggerated elevational view of the improved plunger and a specially constructed contact member carried by the stem thereof;

Figure 5 is a view like Figure 2 but showing a modified switch construction, a switch which is used for operating an oil pressure indicating signal;

Figure 6 is a cross section on the line 66 of Figure 5, looking in the direction of the arrows.

It is obvious that switches as herein shown are susceptible of practical use in connection with electrical signalling and warning signals of many and various styles, but for simplicity it is to be pointed out that the switch appearing in Figures 1 to 4 inclusive is a so called stop light switch, while the one seen in Figures 5 and 6 is an oil pressure switch. Basically and fundamentally the novel characteristics are the same in both forms of the invention.

Attention is first invited to Figures 1 to 4 and particularly to Figure 1 where the numeral 8 denotes, generally, a master cylinder of a hydraulic brake system used on the present day vehicles, the same having a fitting H] with which the oil line I2 is connected and having a coupling M to which the improved stop light switch i6 is detachably connected in the manner shown.

As better shown in Figure 2 the casing of the switch is provided with flat tool gripping surfaces l8 on its exterior. The casing embodies a suitably proportioned and shaped chamber 28, said casing being closed at one end as at 22.

The opposite end is open and a closure of insulation material 24 is fitted therein and held in place as shown by the clenched or inturned retaining lip 26. This closure is provided with a pair of terminal posts 28 and 30 which accommodate the conductive wires 32 and 34 appearing in Figure 1. The relatively fixed contact clips are electrically connected with the posts in the manner shown in Figure 2 and may be perhaps best described as spring fingers 36-36 having return bends 38 defining springy contact elements. 7

The closed end portion 22 is centrally formed with a cylinder 48 one end portion of which projects exteriorly of the bottom 22 and is provided with screw threads 42 providing an attaching neck for use in the manner depicted in Figure l. The interior of the bottom is cast or otherwise formed to provide a boss or protruding portion 44 which is a continuation of the cylinder and which is provided with a conical abutment 46 providing a stop and also a seal; that is, one surface of the complete seal. The plunger 46 is constructed for proper operation in the cylinder and this has a ring groove 56 as shown in Figure 4 to accommodate a packing ring of absorbent material 52. Also, as shown in Figure 4;, the inner portion of the piston has a conical shoulder 54 which precisely matches the shoulder and seat 46 and has, in addition, a reduced axial stem 56 projecting beyond the shoulder and operating through an axial guide opening provided in the boss 44. It will be noticed that the stem is of insulation material and has an axial bore 56 which opens through the right hand or inner end of the stem as best shown in Figure 2. It also has lateral communicating orifices or ports 59 and 66 which constitute vents. That portion of the stem which protrudes through the boss carries a novel relatively movable contact member 62 having a socketed body portion 64 into which the stem telescopes and is frictionally held and has an outstanding marginal flange 66 which serves as a seat or support for one end of the spiralled coil spring 68. The extension is tapered or of conical form and terminates in a needle point 12 which coacts with a diametrically opposite contact element 38. As before stated this needle point and contact assembly affords a self-cleaning coaction between the circuit make and break contact members.

Reverting to the features 12 and 38 this construction provides a heavy duty self-polishing arrangement and keeps small particles of metal from sticking and building up on the needle point. The plunger will have to be timed so that the needle will slide approximately one-sixteenth of an inch after it has made contact with the point, this aifording the self-polishing result.

It will be obvious that when the plunger 48 responds to fluid pressure exerted thereon it serves to close the circuit against the tension of the spring means 68 and brings the shoulder 54 against the seat 46, thus providing the desired valving and sealing effect. The higher the pres- .sure of oil against the plunger the tighter the seal becomes. This is Very important in the stop light signal switch, as the modern booster brake puts more than a thousand pounds of pressure on the brake line. Fluid will not leak by this seal at high pressure. Another important part these shoulders do is to make a stop for the plunger, which means that low and high pressure operate the switch in the same manner without additional wear or strain on any part of the switch. Extreme pressure, heat or cold will not affect the seal. The plunger is put in at bottom of cylinder and a cap (the needle valve 62 here) fits tight on top of plunger which holds it in the cylinder.

Using a felt ring is suggested as it will hold oil or brake fiuid and keep the plunger properly lubricated at all times even if the switch has not been in use for several months. It also makes a low pressure fiuid seal, keeps brake fluid out of switch while brakes are not being used, which makes it a very important improvement.

It is obvious that when the contact member 62 is fitted over the end of the stem 56 air pressure is relieved by way of the bore 58 and ports 59 and 60, it also allows ports 69 and (it provide the desired breather effect and facilitates proper operation of the plunger in the cylinder.

Taking up now the oil pressure switch in Figures 5 and 6 this is denoted as unit by the numeral [6a. The flat faces are denoted at 14 and the chamber at 16. The closure of insulation is denoted at 78 and this is held in place by a lip 88. The terminal post 82 has a metal disc or flange 84 centered in a recess in the insulation 18 against which the adjacent coil or convolution of the helical coil spring 86 bears. The opposite end of the spring bears against a flange 88 on a cap 90 fitting over the end of the stem 92 of the plunger 94, and here again there is a boss 96 projecting into the chamber from the bottom 98, said boss having a shoulder and seat Hill to accommodate the correspondingly shaped shoulder I02 on the plunger. The plunger has a felt packing I04 operating in the cylinder )6 said cylinder being screw threaded at I66, all in the manner previously described. In practice, the terminal (not shown) is plugged into the post 82. Obviously, the light will come on when the ignition is turned on. When the motor is started up and the oil pressure is built up to a certain pressure determined by the coil spring used in the switch, the plunger will push cap off of its ground seat, breaking the circuit, and the light will go out.

A careful consideration of the foregoing description in conjunction with the invention as illustrated in the drawings will enable the reader to obtain a clear understanding and impression of the alleged features of merit and novelty sufficient to clarify the construction of the invention as hereinafter claimed.

Minor changes in shape, size, materials and rearrangement of parts may be resorted to in actual practice so long as no departures are made from the invention as claimed.

Having described the invention, What is claimed as new is:

1. An electric signal controlling switch comprising a casing open at one end, closed at the opposite end, exteriorly fiat faced and having a switch chamber of cylindrical form, the closed end of said casing having an axially centered. integral cylinder, a closure of insulation material mounted in and closing the otherwise open end of said casing, said closure being provided with fixed contact means and complemental terminal post means, a relatively movable contact member in said chamber, said member having'a marginal flange, a coil spring in said chamber hearing at one against said flange and at its cpposite end against said closure, an oil pressure responsive plunger reciprocable in said cylinder, said plunger being provided with a packing ring cooperable with the Wall of the cylinder, the closed end of said casing having a restricted guide opening, and a portion of said plunger being slidable in said guide opening and being operatively connected with said movable contact member.

2. The structure defined in claim 1, wherein said fixed contact means embodies spring metal fingers having return bent terminal end portions in diametrically opposed relation, said spring being a spiral spring, one end of which bears directly against said closure, and said movable con tact member having an axial needle point projectible between and having self-cleaning and wiping engagement with said return bent terminals.

3. As a new manufacture, a plunger construction comprising a cylindrical piston having a packing ring groove, having a conical end portion providing a shoulder and having a reduced stem projecting axially beyond said shoulder, said stem being of insulation material having an axial bore opening through the outer end of the stem and having longitudinally spaced venting ports communicable with said bore, and a contact member having a socketed body with a spring supporting flange and a needle point contact element, said stem telescoping removably into the socket in said body and the latter being spaced from said ports.

4. An electric signal controlling switch comprising a casing which is open at one end and closed at its opposite end, said closed end having an axially centered outstanding cylinder of small cross section, the outer end of said cylinder being screw threaded and open, the opposite end of said cylinder being of truncated conical form and providing a seat and a central guide opening, a plunger fitted in and slidable in said cylinder, said plunger having a single endless groove with a compressible packing ring therein and said ring being of absorbent material, said plunger having a stem and said stem being of insulation material and being snugly fitted in and slidable through and beyond the guide opening into said casing, the end of the plunger at its point of juncture with said stem being of conical form and providing a sealing shoulder engageable with said seat, a contact member removably and telescopically fitted over the projecting end of said stem and located in the chamber of said casing, a closure for the open end of the casing provided with contact means, and a coil spring in the chamber of the casing engaging said closure at one end, said contact member having an end thrust flange and the adjacent end of said spring engaging said flange.

WILLIAM P. BILLINGS,

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 844,262 Dieterich Feb. 12, 1907 1,202,577 Peschman Oct. 24, 1916 1,542,931 Foote June 23, 1925 2,556,209 Negro June 12, 1951 

